Measurement of the Mass Specific Extinction Coefficient for Acetylene and Ethene Smoke Using the Large Agglomerate Optics Facility.
Measurement of the Mass Specific Extinction Coefficient
for Acetylene and Ethene Smoke Using the Large
Agglomerate Optics Facility.
Mulholland, G. W.; Choi, M. Y.
Combustion Institute, Symposium (International) on
Combustion, 27th. Proceedings. Volume 1. August 2-7,
1998, Boulder, CO, Combustion Institute, Pittsburgh, PA,
1515-1522 pp, 1998.
combustion; smoke; acetylene; agglomerates; light
The mass specific extinction coefficient of smoke
produced from acetylene and ethene fuel burned under
laminar and turbulent conditions was measured using the
Large Agglomerate Optics Facility. Key design features
that enable a threefold reduction in the uncertainty
compared with previous measurements include a 10-times
longer pathlength, less than 0.05% drift in the light
intensity ratio, steady-state smoke generation and
dilution, accurate flow calibration, and more precise
filter weight measurements. The measurements are
consistent with previous results obtained for smoke from
avariety of fuels for both small- and large-scale fires.
Specifically, of 7.80 m2/g for acetylene smoke produced
by a turbulent flame using the new apparatus, is in
excellent agreement with 7.82 m2/g as reported by Choi
et al. for the same fuel. However, these values are
significantly larger than the value of 4.5 m2/g obtained
from the study of Wu et al. for acetylene smoke from
turbulent flames. The reliability of the present
experimental measurements is supported by an absolute
calibration using an aerosol comprised of particles of
known size, density, and refractive index. The measured
values in this study appear to be inconsistent with the
values of the refractive index of smoke widely used in
the combustion community. Measurements of the specific
extinction coefficient for acetylene and ethene smoke
indicate depends on fuel type but displays little
dependence on flame conditions (laminar or turbulent
cases). For ethene smoke, the average specific
extinction coefficient is 12% higher than for acetylene
smoke. The larger may be due to a beam-shielding effect
that is dependent on the primary particle size and the
number of spheres comprising an agglomerate.